A hearing aid device includes: a hearing aid housing surrounding an inner space; a frame structure arranged in the inner space, the frame structure configured for mounting at least a microphone and a signal processing unit; a sound emitter sized for being arranged in an ear canal; a conductor, wherein the sound emitter is arranged on a first end of the conductor; a connector socket arranged in the frame structure, wherein the hearing aid housing comprises a passage located in front of the connector socket; a connector plug arranged on a second end of the conductor, the connector plug configured for insertion through the passage for connection to the connector socket; a recess at an outer surface of the connector plug; and a locking plug having a first part configured to extend through a housing opening at the hearing aid housing, and engage with the recess.